A novel patty of plastic food material, such as ground meat and the like, as well as novel methods and apparatus for forming the patty, have been developed wherein, inter alia, the food material is forced through cavities or apertures of a foraminous member into a mold to form a patty in which the food material defines interstitial voids for entrapping air and providing retention of cooking juices to promote more rapid and uniform cooking of the patty. Such methods and apparatus are disclosed in the Harry H. Holly U.S. Pat. Nos. 4,272,864 and 4,338,702.
The U.S. Pat. Nos. 4,356,595 and 4,372,008 to Sandberg et al. disclose apparatus for forming a meat patty by forcing ground meat under pressure through a foraminous member which defines a plurality of orifices.
In the embodiments illustrated in the above-discussed U.S. Pat. Nos. 4,272,864, 4,338,702, 4,356,595, and 4,372,008, each of the cavities, apertures, or orifices defined in the foraminous member are of circular cross section, and each define, for at least part of the thickness of the foraminous member, a cylindrical bore within the foraminous member. The bores are each oriented with the bore longitudinal axis perpendicular to the planar surfaces of the foraminous member and perpendicular to the plane of the patty mold cavity opening.
A patty formed from food material forced through such a foraminous member can have increased void space for trapping air and retaining cooking juices. However, if the discrete extrudate masses of food material in the patty are not also sufficiently cohesive or interlocked, there is a tendency for the patty to break or fall apart when subjected to excessive handling or processing.
Accordingly, it would be desirable to provide an improved patty with the desired void structure but also with an improved structural capability for resisting breakage and internal separation. It would also be desirable to provide an improved method and apparatus for making such an improved patty.
As is discussed in detail in U.S. Pat. Nos. 4,272,864 and 4,338,702, many ground food materials, and especially ground meat, contain string-like tissue fibers which, when the food material is formed into a patty, are distributed within the patty. When such material is initially ground, the tissue fibers are essentially "balled" up, so that their string-like nature is not visibly apparent.
However, when the ground material is moved across stationary contacting surfaces in a molding machine during formation of the patty, some of the tissue fibers unwind and may become aligned in the direction of movement of the ground material and/or patty (or in the direction of movement of any surface moving against a stationary patty or mass of ground material). When the patty is cooked, the tissue fibers contract during the cooking process and cause a shrinkage of the patty in the direction of tissue fiber alignment. The patty does not shrink as much in the direction perpendicular to the aligned tissue fibers so that the resulting patty, though initially formed with a circular shape, assumes a somewhat oval shape after cooking.
In contrast, with the patty formed in accordance with the teachings of U.S. Pat. Nos. 4,272,864 and 4,338,702, forces tending to unwind the tissue fibers are minimized so that the tissue fibers are generally randomly distributed in one or more of plugs of material and are not as readily unraveled into a generally straight line configuration when the patty surface is subject to friction forces in one direction, as when transferring the patty in a mold transfer plate from one position to another. Since the tissue fibers do not as easily unravel from a random orientation within each plug (or from within a small number of adjacent plugs), the generally random orientation of the tissue fibers in the patty is generally maintained. While patties formed in accordance with the teachings of U.S. Pat. Nos. 4,272,864 and 4,338,709 represent a marked improvement over prior art patties insofar as maintaining a generally circular shape after cooking, nevertheless some slight out of roundness may still occur. This can be caused by tissue fiber alignment in the shear layer that is present at one or both sides of the patty and that is created as the mold plate moves the formed patty to a patty ejecting position.
Thus, it would be desirable to provide an improved patty of the type formed by forcing meat through apertures in a foraminous member which would be truly circular upon cooking, and to provide a method and apparatus for forming such a patty.
When food material that contains tissue fibers, especially meat and the like, is forced through a foraminous member, opposite end portions of a single tissue fiber can be forced into different apertures in the foraminous member. The fibers, being stringy and thin, are not easily severed under the influence of conventional molding pressures.
A number of such fibers may be forced against the upstream side of the foraminous member in a manner that tends to plug up the foraminous member apertures. This tendency of tissue fibers to plug up foraminous member apertures was identified by Harry H. Holly and is described in detail in the above-identified U.S. Pat. No. 4,272,864 with reference to FIG. 23 of that patent.
Some of the apparatus and methods disclosed in some of the above-discussed U.S. patents are intended to function, at least with certain types of food material, so as to minimize or prevent the plugging up of the foraminous member with tissue fibers on the upstream side of the foraminous member. However, it would be desirable to provide a less complex method and apparatus for preventing plugging by tissue fibers, as well as to provide a method and apparatus that would be very effective with a great many types of food material.
Further, it would be beneficial if such an improved method and apparatus could be effected with a minimum of movement of the food material so as to avoid the undesirable effects of excessive working of the food material. Excessive working of some types of food material, such as ground beef, can make the food material less tender.
Finally, it would be advantageous if apparatus could be provided for quickly and easily converting conventional patty molding machines to the improved type of molding machine wherein the food material is forced through a foraminous member and wherein the "conversion" apparatus has the capability for dislodging tissue fibers from the upstream side of the foraminous member so as to avoid or minimize plugging up of the apparatus.